return DMA_30BIT_MASK;
 }
 
+static enum b43legacy_dmatype dma_mask_to_engine_type(u64 dmamask)
+{
+       if (dmamask == DMA_30BIT_MASK)
+               return B43legacy_DMA_30BIT;
+       if (dmamask == DMA_32BIT_MASK)
+               return B43legacy_DMA_32BIT;
+       if (dmamask == DMA_64BIT_MASK)
+               return B43legacy_DMA_64BIT;
+       B43legacy_WARN_ON(1);
+       return B43legacy_DMA_30BIT;
+}
+
 /* Main initialization function. */
 static
 struct b43legacy_dmaring *b43legacy_setup_dmaring(struct b43legacy_wldev *dev,
        dma->tx_ring0 = NULL;
 }
 
+static int b43legacy_dma_set_mask(struct b43legacy_wldev *dev, u64 mask)
+{
+       u64 orig_mask = mask;
+       bool fallback = 0;
+       int err;
+
+       /* Try to set the DMA mask. If it fails, try falling back to a
+        * lower mask, as we can always also support a lower one. */
+       while (1) {
+               err = ssb_dma_set_mask(dev->dev, mask);
+               if (!err)
+                       break;
+               if (mask == DMA_64BIT_MASK) {
+                       mask = DMA_32BIT_MASK;
+                       fallback = 1;
+                       continue;
+               }
+               if (mask == DMA_32BIT_MASK) {
+                       mask = DMA_30BIT_MASK;
+                       fallback = 1;
+                       continue;
+               }
+               b43legacyerr(dev->wl, "The machine/kernel does not support "
+                      "the required %u-bit DMA mask\n",
+                      (unsigned int)dma_mask_to_engine_type(orig_mask));
+               return -EOPNOTSUPP;
+       }
+       if (fallback) {
+               b43legacyinfo(dev->wl, "DMA mask fallback from %u-bit to %u-"
+                       "bit\n",
+                       (unsigned int)dma_mask_to_engine_type(orig_mask),
+                       (unsigned int)dma_mask_to_engine_type(mask));
+       }
+
+       return 0;
+}
+
 int b43legacy_dma_init(struct b43legacy_wldev *dev)
 {
        struct b43legacy_dma *dma = &dev->dma;
        enum b43legacy_dmatype type;
 
        dmamask = supported_dma_mask(dev);
-       switch (dmamask) {
-       default:
-               B43legacy_WARN_ON(1);
-       case DMA_30BIT_MASK:
-               type = B43legacy_DMA_30BIT;
-               break;
-       case DMA_32BIT_MASK:
-               type = B43legacy_DMA_32BIT;
-               break;
-       case DMA_64BIT_MASK:
-               type = B43legacy_DMA_64BIT;
-               break;
-       }
-
-       err = ssb_dma_set_mask(dev->dev, dmamask);
+       type = dma_mask_to_engine_type(dmamask);
+       err = b43legacy_dma_set_mask(dev, dmamask);
        if (err) {
 #ifdef CONFIG_B43LEGACY_PIO
                b43legacywarn(dev->wl, "DMA for this device not supported. "